Assessing continuum postulates in simulations of granular flow
Continuum mechanics relies on the fundamental notion of a mesoscopic volume"element" in which properties averaged over discrete particles obey deterministic relationships. Recent work on granular materials suggests a continuum law may be inapplicable, revealing inhomogeneities at the particle level, such as force chains and slow cage breaking. Here, we analyze large-scale three-dimensional Discrete-Element Method (DEM) simulations of different granular flows and show that an approximate"granular element" defined at the scale of observed dynamical correlations (roughly three to five particle diameters) has a reasonable continuum interpretation. By viewing all the simulations as an ensemble of granular elements which deform and move with the flow, we can track material evolution at a local level. Our results confirm some of the hypotheses of classical plasticity theory while contradicting others and suggest a subtle physical picture of granular failure, combining liquid-like dependence on deformation rate and solid-like dependence on strain. Our computational methods and results can be used to guide the development of more realistic continuum models, based on observed local relationships betweenaverage variables.
- Research Organization:
- Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
- Sponsoring Organization:
- Computational Research Division
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 953685
- Report Number(s):
- LBNL-63631-JArt
- Journal Information:
- Journal of the Mechanics and Physics of Solids, Journal Name: Journal of the Mechanics and Physics of Solids; ISSN JMPSA8; ISSN 0022-5096
- Country of Publication:
- United States
- Language:
- English
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